I'd try English first, especially with younger people, simply because a lot of youngsters don't know Russian. Perhaps the older people will be happy to use Russian, particularly if they don't speak English. I find it with German, many older people automatically speak to me in german, even if I try speaking Polish to them.
I was teached that hidden truth the hard way in France long time ago, when I tried to use English without warning :-)
Haha, yes. My boss at the language school (He's Polish) complained to me that he'd been to France and asked for a menu in English and found the waiter unhelpful. I cringed at his story. I had to explain that the French are pretty proud of their language and there are only three ways to converse with them... NEVER just ask if they speak English.
1) Speak fluent French,
2) Speak such bad French that it hurts their ears. They will suddenly develop great English. They are more likely to reveal their English if they feel you are trying to respect that they are French and speak French (fair enough, really)
3) Speak any other language (except maybe German) and make it clear you don't speak French. They might then ask if you speak English.